This invention relates to cooling a component that is used in an elevated temperature environment and, more particularly, to an article and method for increasing effectiveness of cooling the component.
A variety of different machines, such as gas turbine engines, typically include components that operate under elevated temperatures. To resist the elevated temperatures, the components traditionally employ a cooling system. For example, gas turbine engines utilize turbine blades having a film cooling system. Typical film cooling systems include passages within walls of the turbine blade that carry relatively cool air taken from an air flow through the engine. The passages open to outer surfaces of the turbine blade and discharge the cool air as a film over the surfaces to maintain the blade below a certain temperature.
Typical film cooling systems have the problem that the discharged film mixes with a hot gas flow over the surfaces to thereby reduce cooling effectiveness. One solution is to increase the discharge flow of the air from the passages, however, this requires an increase in air taken from the air flow through the engine, which reduces efficiency of the engine.
Another solution includes utilizing a trench formed in a coating that is on the outer surface of the turbine blade and discharging the air into the trench. The trench provides shelter from the hot gas flow such that the discharged air can remain in contact with the walls of the turbine blade to provide cooling. Although effective, once the cool air flows out of the trench, it mixes with the hot gas flow and the cooling effectiveness decreases as a function of distance from the trench. Again, increasing the discharge flow of the air would provide more effective cooling over a longer distance, but at the cost of reducing engine efficiency.
Therefore, what is a needed is an arrangement and method for providing enhanced cooling without having to increase the flow of the cooling air. This invention addresses these needs while avoiding the shortcomings and drawbacks of the prior art.